Construction of TiO2/SnIn4S8 heterojunction to promotion photogenerated carrier separation and enhance photocatalytic hydrogen production via superoxide radical active species

The high recombination rate of photogenerated electron-hole seriously affects the photocatalytic hydrogen production performance of TiO2. Meanwhile, the lack of clarity of the active species in photocatalytic hydrogen production poses a certain obstacle for catalyst modification. To solve this problem, TiO2/SnIn4S8 (TS) type II heterojunctions were prepared in this study, and TS composites achieve rapid separation and fast transfer of electron-hole. TPR results showed that the photocurrent of TS-10 increased from 2 μA/cm2 to 14 μA/cm2. In addition, the results of active species trapping experiments showed that the superoxide radicals (·O2-) were the main active species in the photocatalytic hydrogen production of TS-10. As a result, TiO2/SnIn4S8 exhibited highly efficient photocatalytic hydrogen production performance. The hydrogen production rate of the optimal ratio of TS-10 reached 1603.47 μmolg-1h-1, which was 16 times higher than that of pure TiO2, and the apparent quantum efficiency (AQY) reached 2.064%. This study clarifies the active species in photocatalytic hydrogen evolution and provides new ideas for designing materials with high photocatalytic hydrogen evolution performance.